渭北旱塬免耕/深松轮耕麦田产量和土壤水分对施肥的响应模拟

Simulating Wheat Yield and Soil Moisture under Alternative No-tillage and Subsoil Tillage in Response to Fertilization Levels in Weibei Highlands

为探索不同肥力水平对渭北旱塬连作冬小麦田在长周期免耕/深松轮耕措施下土壤蓄水保墒和作物增产效应的影响,在模拟精度验证基础上,应用WinEPIC模型长周期定量模拟研究了1980–2009年渭北旱塬免耕/深松轮耕连作麦田5个不同施肥水平下（T1, N 75 kg hm–2＋P2O560 kg hm–2； T2, N 120 kg hm–2＋P2O590 kg hm–2； T3, N 150 kg hm–2＋P2O5120 kg hm–2； T4, N 180 kg hm–2＋P2O5150 kg hm–2； T5, N 255 kg hm–2＋P2O590 kg hm–2）冬小麦产量和土壤水分效应。在30年模拟期间,各处理的冬小麦产量、年度耗水量和水分利用效率均呈波动下降趋势,下降幅度表现为T5〉T4〉T3〉T2〉T1。0~5 m土层土壤有效含水量呈季节性波动降低趋势,且随施肥水平的升高而降低,5个处理的麦田平均干燥化速率依次为每年13.5、17.1、17.4、20.1和23.9 mm。0~1.5 m土层土壤湿度随季节降水波动；各处理在不同深度形成稳定的土壤干层,其中T1在1.5~2.0 m, T2和T3在1.5~3.0 m, T4和T5在1.5~4.0 m。上述结果表明,随着肥力水平的增加,旱作冬小麦产量和耗水量也增加,土壤干层加厚。综合考虑认为,在渭北旱塬免耕/深松轮耕长期连作小麦田适宜的施肥量为纯氮150 kg hm–2＋P2O5120 kg hm–2。

This study aimed at understanding the responses of grain yield and soil moisture to fertilization level in dryland winter wheat under long-term alternative no-tillage and subsoil tillage. The WinEPIC model was employed on the basis of precision veri-fication with five fertilization levels （T1, N 75 kg ha–1＋P2O5 60 kg ha–1; T2, N 120 kg ha–1＋P2O5 90 kg ha–1; T3, N 150 kg ha–1＋P2O5 120 kg ha–1; T4, N 180 kg ha–1＋P2O5 150 kg ha–1; and T5, N 255 kg ha–1＋P2O5 90 kg ha–1） and the simulation period was from 1980 to 2009. During the 30-year period, water consumption in the growing season and water use efficiency of winter wheat tended to decrease in a fluctuating manner at different fertilization levels with the ranking sequence of T5〉T4〉T3〉T2〉T1. In the 0–5 m soil depth, the monthly available soil moisture tended to decrease in a seasonally fluctuating manner and reduced with the increase of fertilization amount. The soil desiccation rates from T1 to T5 were 13.5, 17.1, 17.4, 20.1, and 23.9 mm per year, respectively. During the simulation period, the soil humidity in 0–1.5 m soil layer fluctuated with the seasonal rainfall. A stable dry soil layer was found under all fertilization levels which was 1.5–2.0 m under T1, 1.5–3.0 m under T2 and T3, and 1.5–4.0 m under T4 and T5. These results indicate that grain yield and water consumption of winter wheat may increase with more fertilizer input, however, the dried soil layer is thickened. In a comprehensive consideration, we suggest N 150 kg ha–1＋P2O5 120 kg ha–1 to be the optimal fertilization rates in winter wheat under long-term alternative no-tillage and subsoil tillage in Weibei Highlands.